Rapid rises in income can lead to obesity among adults, even in households where children remain undernourished. New research suggests a way to prevent this “double burden” of malnutrition.

In many low- and middle-income countries, strong economic growth is increasing household incomes and helping reduce child stunting—but not as fast as it’s pushing up overweight and obesity among women. The resulting coexistence of overnutrition and undernutrition, sometimes even in the same household, is now common enough that nutritionists have given it a name: the double burden of malnutrition.

How do you ensure that extra income improves children’s nutrition without harming parents’ nutrition? A team of researchers from IFPRI, Cornell University, and Mexico’s Instituto Nacional de Salud Pública (INSP) examined this question by looking at the double burden among poor, rural households in Mexico, which has one of the highest rates of obesity globally. They found, says IFPRI Senior Research Fellow Jef Leroy, that one key to maximizing the nutritional benefits of income growth while minimizing its downside is educating mothers.

Unintended effects

In 2003, the Mexican government launched the Programa de Apoyo Alimentario (PAL), which provides poor, rural households living in remote areas with either a cash transfer or a basket of food of equivalent value each month. An INSP evaluation of the program showed that PAL, like similar cash and in-kind transfer programs in Mexico and other countries, effectively increased the wealth of recipient households but had only a limited impact on child stunting.

To look more closely at how the program affects the nutrition of participating households, Leroy and several coauthors conducted additional analyses of the data. One of these studies showed that after 14 months in the program, PAL recipient households consumed a more nutritious and diverse diet compared with nonparticipants, and their overall energy consumption increased.

Higher energy consumption could be a boon for a population suffering from energy deficits at the onset, but in this population two-thirds of women had been overweight or obese when they entered the program. Another study revealed that PAL actually led to excessive weight gain in women, and that the largest weight gains were among women who were already obese before participating in the program.

Flip the switch

Is there a way to prevent increases in income from leading to weight gain in adults? Leroy and his colleagues, including Marie Ruel, director of IFPRI’s Poverty, Health, and Nutrition Division, hypothesized that education might be key.

“Previous work had shown how education operates as a sort of switch,” says Leroy. “If education of a mother is high, then you see that kids grow better with increasing wealth—and if education is low, you don’t see that effect.”

To investigate the effect of maternal education on the double burden of malnutrition, Leroy and his collaborators used data on 1,547 mothers and their children living in the 235 PAL study communities in southern Mexico. They assessed whether or not a mother’s completion of primary school acted as a “switch” that helped promote the positive effects of income growth on children’s nutrition and lessen the negative effects on women’s nutrition.

The results of their study, published recently in the Journal of Nutrition, support the idea of an education switch. For mothers who did not complete primary school, a doubling in household wealth was associated with a 3.7 percent increase in the mother’s weight and no improvement in child height. For mothers who completed primary school, the reverse was found: when household wealth doubled, child height rose and the mother’s weight stayed steady.

“The switch effect had not been shown before for maternal weight,” says Leroy, “and it also had not been shown for both of these outcomes in the same mother-child pairs.”

Targeted teaching

These results do not make it any less urgent or necessary to raise the incomes of poor households. They do suggest, however, that increasing household income through poorly designed programs may not only fail children, but may also exacerbate the problem of overweight and obesity, at least among less educated women.

And it’s not necessary to send the women back to primary school. “Enhancing women’s nutrition knowledge through behavior change communication can compensate, at least in part, for lack of education,” says Ruel, “and help translate rises in income into positive nutrition outcomes.”

The research shows, says Leroy, that it takes more than cash or food transfers to make a dent in malnutrition in all its forms.

“To me, the bottom line is that we shouldn’t just throw money or resources at people, but we should also make sure that they know how to use those resources in a way that helps them live a healthier life,” he says. “In that sense, providing women with better knowledge is a wise thing to do.”

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